Scientific studies have shown that minoxidil is effective in the front areas of the scalp, as well as the vertex area in male pattern hair loss. At the conclusion of one 48 week study, improvements were seen in the frontal scalp regions of 51% of men using 5% minoxidil, 42% using 2% minoxidil, and 13% of placebo users. Among these men, moderate to great increases in hair growth were seen in the frontal scalp regions of 19% of men using 5% minoxidil, 10% using 2% minoxidil, and 3% of placebo users.

It has also been shown that any benefits are lost when Minoxidil treatment is ceased. Therefore to maintain any hair growth the use of Minoxidil must be maintained on an ongoing basis.

The method of action for Minoxidil is not known. It is not just the vasodilating effects which cause the hair regrowth, as no other vasodilator has been shown to be effective in treating hair loss.